1. Field of the Invention
The present invention relates to dental and surgical instruments. More particularly, the present invention relates to a handpiece having a disposable cartridge assembly containing a turbine, shaft and bearing.
2. Problems in the Art
According to data released by the American Dental Association, infection control is the second largest area of concern to dentists. The rise in concern of infection control is in a large part due to recent documentation which demonstrates that disease can be transmitted in the dental office by blood and saliva retained in the turbine, shaft and bearings of a high speed handpiece. Infection control, specifically with a high speed handpiece, has become a public concern after reports of patients reportedly contracting the HIV virus at their dentist office. Additional research links nosocomial infections in the dentist office directly to the use of the high speed handpiece.
The concern of infection control is not limited to the transmission of the HIV virus, but also includes the transmission of Tuberculosis, Pneumonia, Influenza, the common cold, Oral Herpes, and possibly the transmission of Hepatitis B.
As a result of the growing concern of transmission of diseases between patients, dentists have had to conform to more stringent cleaning and sterilization procedures for their handpieces. Included in those procedures is autoclaving handpieces after each patient. Autoclaving is a process of sterilization that heats the handpieces above 250.degree. F. for a certain amount of time to kill germs. A "cool-down" period is then required before the handpiece can be used on another patient.
The combination of the air, water, and the high speed rotation of the drilling bur creates an aerosol, which includes tissue, blood, and saliva, that is drawn up into the turbine, shaft, and bearings of the handpiece along with the residual lubricants left in the handpiece. For proper cleaning of a typical prior art handpiece, the drill bur must be removed from the handpiece. The top is then removed from the head of the handpiece, generally by unscrewing a cover plate, and the turbine, shaft and bearings are then removed and then cleaned and autoclaved. Damage to the various parts can result if care is not taken. The handpiece is easily cleansed and autoclaved since it has no small intricate moving parts once the turbine, shaft and bearings have been removed.
Currently, it is difficult to properly clean the complete handpiece assembly prior to autoclaving. While the turbine, shaft, and bearings are separable from the tube structure of the handpiece, they are difficult to clean and sterilize due to their small intricate design. The empty handpiece is more easily cleaned and sterilized.
The residual debris found in the mechanisms of the handpiece can contain and trap microorganisms which were drawn up into the turbine, shaft, and bearings. The microorganisms can later migrate back down the drill bur or into the handpiece channels where they can harbor, multiply, and be forcibly introduced into the body tissues of subsequent patients.
Since the turbine, shaft, and bearings are not changed from patient to patient, cross contamination is probable.
The transmittal of organisms associated with diseases such as Tuberculosis, Oral Herpes, Hepatitis and HIV via the handpiece assembly is of prime concern due to the potential introduction of high concentrations of microorganisms into the oral cavity.
A conventional high-speed dental handpiece assembly is connected at one end to a base coupler assembly which provides fluid and air under pressure. The opposite end (head) contains the chamber housing the components necessary to provide high speed rotation under air pressure (typically, the turbine, shaft, and bearings). Conventionally, the air pressure rotatably drives the turbine which contains a shaft with a chuck designed to grip the cutting bur. This design normally requires a chuck tool to tighten the chuck onto the bur and to loosen the chuck when removing the bur. The chuck can be over tightened distorting and causing damage to the chuck. Due to under tightening, or slight variances in bur shank size, the bur can slip, and not rotate or cut properly. Also, debris can get lodged in the chuck. A dentist can waste a significant amount of time looking for the bur tool, untightening the chuck, replacing a cutting bur, retightening the chuck, and removing the bur tool. If this procedure is not performed correctly, or if the shank of the bur is undersized, or if debris is present in the chuck, the cutting bur may slip and not cut properly.
The extreme heat of autoclaving causes any remaining lubricants, blood, tissue, and saliva to bake into the turbine, shaft and bearings, eventually causing "lock-up" of the internal moving parts.
It can be seen that the cleaning and sterilization process is costly and time consuming. Not only is the procedure itself costly and time consuming to a dentist, but the autoclaving and cool-down between patients requires additional handpieces. The performance of the handpiece assembly is reduced as repeated autoclaving adds to the build-up of baked on debris which can result in smaller patient loads due to scheduling around autoclaving or increased personnel to clean and autoclave on a more rapid interval.